Eff Oh,. .I wear prescription glasses in the cockpit, and being the stingy sort (i.e. still a regional airline FO) I have been unwilling to buy any new sunglasses. I have found the adjustable sunblocker in the cockpit does an adequate job of blocking the sun even if flying directly into it. It is quite dark, but you can easily pick out air traffic through it when the sun is in your eyes.
I will also pull up the yellow colored sun shade on the side window if the sun is really bright from the side. However, it is not as easy to see through (especially when they get old and krinkled up), so I will only pull that up in the flight levels.
Maybe when I make Captain I will be able to afford some nice prescription sunglasses. I rarely find myself wishing I had some, though. <img src="smile.gif" border="0">